Description:
Tiny stepper motor based clock (including base, L=80mm, W=80mm, H=127mm)
The clock face is 50mm in diameter with a 5mm wide clear / slightly opaque ring around it for a total diameter of 60mm.
Behind the clock face is an LED ring with 12 WS2812 LEDs that light up every hour and play a short animation.
The stepper motors used in this clock are very weak so a lot of care need to be taken to align the shafts properly and for the gears to be running as true as possible on the shafts.
Each stepper motor has 20 fullsteps per revolution which with a gear reduction of 3:1 gives 60 steps per revolution.
The minute hand takes a step every minute while the hour hand takes a step every 12 minutes.
Since this is the tiny version that implies the existence of a bigger stepper motor based clock. The bigger version can be found here: StepperClock
Waring: The clock is mains powered and there are a few somewhat exposed live traces / metal contacts so build and use at your own risk.

Building:
Create all parts needed as shown in the FreeCAD drawing.
Assemble as shown on the pictures and in the FreeCAD drawing.
A lot of care needs to be taken to be as precise as possible as there isn't much room for tolerance in this design due to the weak motors and tiny gears.
Also a lot of parts are press fit together (bearings in holders, motors in holders, clock face in clear ring, clear ring on LED ring, etc.) so make sure to adjust the design to fit the expacted tolerances of your manufacturing process and the parts you bought. Note that one of the stepper motors is wired in the opposite direction so that the same step sequence can be used to drive them.
If the motors are turning in the wrong direction or both motors were wired the same on accident the code allows for inverting the motor direction as well. When attaching the clock hands to the shaft the clock needs to be powered on (preferably through usb).
That way the stepper motors align with one of their magnetic steps which ensures that the hands can properly point to all positions they need to. Align the clock hands with the 12 o'clock position and solder them in place.

Tools:

• CNC machine or other way to create parts from a piece of flat material as well as for engraving the clock face.
• FDM or SLA printer to create the spacer and the clear ring.
• Depending on the parts you can get and the need to modify them a lathe is very useful.
• Soldering iron, screwdrivers, etc.

Stepper motors:
20 steps per rev
3.3V @ 80mA per coil (gets slightly warm)
Does not like having both coils energized at the same time, gets pretty hot and doesn't step well
Diameter: 8mm
Length: 9.2mm
Gear (from factory): 10 teeth 0.2 module? (2.3mm diameter)
Can be found from multiple sellers in china for very cheap (AliExpress)

Stepper driver:
DRV8833 without current limiting (3.3V straight through)
On a breakout board just soldered onto carrier PCB

Clock hands:
Need to be made of a material that can be soldered to so they can be attached to the shafts.
CNC milling them from some leftover PCB material works great.

Power supply:
The Pi Pico is powered from a 230V to 5V mains power supply "brick" made by Hi-Link which can supply 600mA.
To power the stepper drivers the 3.3V output of the Pi Pico is used. The stepper motors together draw around 160mA at 3.3V with only one of their coils being active at a time.

Needed parts (mechanical):

• 2x 60 tooth gear, 1.4mm thick, 0.3 module
  • one with 4mm hole and one with 2mm hole for the shaft
• 2x 20 tooth gear, 1.4mm thick, 0.3 module
  • with 2.3mm hole to fit onto factory gear of the stepper motor
• 2x Bearing 8mm OD, 4mm ID, 3mm thick
• 1x Bearing 7.3mm OD, 2mm ID, 3mm thick
  • 7mm OD bearings are also available, pick whatever is cheaper and modify the bearing holder design to fit your needs
• 3mm thick material for the frame parts (I used Resopal)
• Brass tube 4mm OD, 2mm ID (shaft for the hour hand)
• Brass tube 5mm OD, 3mm ID (used as spacers for the stacked PCBs)
• Brass rod 2mm (shaft for the minute hand)
• Various M2 and M3 screws, nuts and washers
• A block of wood or other material to make a base for the clock

Needed parts (electrical):

• 2x Stepper motor
  • order more than that because they tend to arrive broken (coil wires ripped off)
• 1x Raspberry Pi Pico without headers
• 1x 5V PSU (Hi-Link HLK-PM01 or pin and size compatible)
• 1x WS2812 LED ring with 12 LEDS (~50mm OD)
  • 8 LED version (~32mm OD) should work too with a modified spacer and a few code changes
• 1x Diode (shotkey or any other type, 1N4007 works just fine)
• 1x Capacitor (At least 5V rating, around 470µF works fine)
• 1x 2.54mm 2 pin screw terminal
• Some 2.54mm pin headers
• Thin wires
• The PCBs from the KiCAD project